Pros do not buy versatile tools. Amateurs do. A pro would buy a camera/lens combination specifically designed for head&shoulders portraits, or for weddings, or for shooting sports. This will often mean having a Hasselblad for studio, a Canon body with a 500mm f/4 for sports and OM-D for street photography.

The basic assertion doesn't make a lot of sense. A pro who shoots under very controlled situations such as a studio or a well known spot on the sidelines at his favorite football stadium will have a good idea what shots are going to come up and what tools maximize getting the shot. On the other hand, a photojournalist or a nature photographer may simply have go out prepared for whatever shots present themselves, even including (relatively crappy by pro standards) video clips. These people are often seen carrying sets of the f/2.8 zooms that you seem to associate with clueless amateurs.

Maybe the most well-heeled pros will use the best specialized tool for each situation (including a professional cameraman for the video clips!), but judging from the average income of professional photographers (and/or the resources provided by the employer/agency), the vast majority are interested in some degree of versatility.

Trying to use logic on people who are fanboi logic and reason doesn't work on them.

I'm having trouble figuring out who the fanboys are. I can make pretty pictures with all my cameras, FX, DX, MFT and sometimes with my iPhone.